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I'm a track junky and was trying to get my new (to me) 991.1 GTS classified for NASA TT and was hoping for TT3 which 10/1 (weight/power).
Today I had the day off, so I ran down to the dyno shop for some pulls. Luckily mine is a manual so no expensive dyno equipment needed like in PDK cars. The car put down bigger numbers than I was expecting, 386 rwhp (I was thinking 365ish) especially for being 110 degrees outside. I did still have 100 octane in there from my recent track day, so maybe that made a difference? Does my dyno graph look right for a 2016 GTS? It's still building power right up to redline? No decline really? I've never had a car do this before on a dyno graph. Are these basically a GT3 motor that has gets stopped at 7600 rpm? Could my car have a tune even though its CPO? The NASA TT3 worksheet takes the highest 7 readings in 250rpm increments, so my average rwhp for NASA came out to 358hp which means I need to weigh 3580 lbs total with me in the car. Now luckily I weigh 300lbs (Or maybe unluckily ) so I think there's a chance..
Weight: Car is totally on empty when I get back home, although I did stop for some wings and beers to bulk myself up. I throw it on the scales and it comes up with 3055. I'm like WTF? I re-zeroed everything and added 5 gallons of fuel and its at 3090 now. After I get in, the scale reads 3243, and I sure as heck didn't lose 50lbs today. I know my scales must be messed up. What should this car weigh?
Last edited by MaynardZed; 07-29-2018 at 03:09 PM.
Reason: better dyno graph with temp and correction
Aren't the numbers with standard correction? Could it be that 110 degree ambient actually worked in your favor applying a bigger temperature correction than the actual power loss due to the temperature?
I think standard (uncorrected) temp is like 77F, not sure how accurate the corrections are when you have such a large difference between standard and actual...
Dyno numbers seem about right. Maybe a tad on the high side but that could be due to the 100 octane... Regardless, I'd be really happy with those numbers.. Your weight seems a little on the low side. What options do you have?
I weighed my new GTS at Wild Horse Pass and it was 3400 pounds on the nose.. Wanna run it? I also live in Scottsdale.
That's what an x51 dyno should look like! The people that say they can't tell the difference between the standard 3.8 and the powerkit motor aren't revving them out.
Yeah it's always been right on for my M3 race car too. I'll just take it to the track and weigh it on their scales. I got some wiggle room back on the NASA TT calculator because I'm going to be running street tires (most guys run Hoosiers). It's saying my minimum weight with driver is 3409 after that adjustment, should be no problem.
Originally Posted by LavaGTS
Dyno numbers seem about right. Maybe a tad on the high side but that could be due to the 100 octane... Regardless, I'd be really happy with those numbers.. Your weight seems a little on the low side. What options do you have?
I weighed my new GTS at Wild Horse Pass and it was 3400 pounds on the nose.. Wanna run it? I also live in Scottsdale.
Yeah, it's a really nice dyno plot. I'll be there on East track early morning 8/25 if you want to run the road course, otherwise I don't I'd have a chance against a .2 in a drag race.
Those numbers are very encouraging, consider we have the same car, just the difference of mine being PDK would give it another couple hundred pounds on top of what yours weighs. Posted numbers from Porsche say 991.1 curb weight is 1,485 kg (3,274 lb) for GTS.
That's awesome if yours doesn't have a tune because that would mean mine is making similar power but I'd venture to guess there's a tune on it as well. Either way, rock on!
Yeah it's always been right on for my M3 race car too. I'll just take it to the track and weigh it on their scales. I got some wiggle room back on the NASA TT calculator because I'm going to be running street tires (most guys run Hoosiers). It's saying my minimum weight with driver is 3409 after that adjustment, should be no problem.
Yeah, it's a really nice dyno plot. I'll be there on East track early morning 8/25 if you want to run the road course, otherwise I don't I'd have a chance against a .2 in a drag race.
I just may have to take you up on that. Drag for fun, no egos or anything stupid like that. You own one of my favorite cars right now and would love to hear that thing rip!
I wouldn't be surprised if my car dyno'd the same or less HP as yours right now. The heat soak is real in this weather. Do you notice any difference between day and night?
385 rwhp would equate to what at the engine? Excuse my noobness about this but just curious since I have pretty much the same exact car (991.1 manual C2 GTS).
385 rwhp would equate to what at the engine? Excuse my noobness about this but just curious since I have pretty much the same exact car (991.1 manual C2 GTS).
Can't say exactly. The Dynojet dyno tends to be a little generous with its readings compared to other types of dynos, But this run still seems to suggest slightly higher than 430 horsepower at the crank.
A good rule of thumb over the years had been 17% driveline loss, but it seems many modern cars lose much less than that. My BMW M4 (turbo powered) put down 415 rwhp on a MAHA dyno from factory (rated 425 hp) and a crap load of torque too. BMW, MB, and many other turbo powered cars are putting down way higher numbers than anticipated on dynos based on factory numbers.
Nevertheless, my N/A GTS putting down a reading of 386rwhp in 110 degree weather is pretty good and I'm happy with it. It could have a tune. Not sure because I bought it used. You would think that it being Porsche CPO they would check on that stuff, but who knows. I guess I can't complain, since I traded in my M4 which has a tune too and I didn't tell them either.
Update on the weight: Yes, the scales at my house are off by about 150lbs. I went down to a track buddies garage today to weigh it on his scales and the car was right where I expected: 3240 lbs with a half a tank of gas. Should be no problem getting into TT3 with this thing and might even be able to run Hoosiers like I originally thought.
The weigh in numbers look about right - the dyno numbers are high for a stock series 1 GTS - they should be about 350HP at the wheels, the series 2 is about 370HP at the wheels (on a dyno that measures losses).
Its very common for dynos to be inaccurate and there are many reasons for this - for example the following is from Cobb "The Carrera GTS offers even larger turbochargers than the Carrera S, the compressor measurements come in at 55mm. With those turbochargers producing right around 18 psi of boost pressure we recorded baseline numbers of 423 HP and 409 TQ measured at the wheels. A simple Stage 1 calibration with 93 octane fuel in the tank took the GTS to an astonishing 506 HP and 488 TQ measured at the wheels, peak gains of over 19%!"
The numbers in bold are inaccurate - however the delta between the numbers is real so a peak gain of around 83HP (or a total peak of around 453HP at the wheels).
You will find that a Porsche, run on a high quality and well calibrated dyno that measures losses will deliver calculated numbers at the crank very much inline with Porsche published figures.
The 991.1 GTS has a seriously special motor in it, and it's why I've enjoyed them more than almost all of my GT cars honestly...The new GTS motor isn't nearly as special vs the standard either :/
07-26-2018, 10:57 PM
991.1 GTS Dyno and weight results too good?
) so I think there's a chance..
